Being pushy might not be a strategy to prompt shoppers to buy or interact with a brand more. But getting shoppers to sign up for mobile push notifications just might, a new study suggests.

“The Good Push Index” released by Urban Airship, a mobile marketing vendor, finds that consumers who opt in to receive push notifications from mobile apps open the app 26% more often on average each month than those who do not opt in to receive those messages. Additionally, 55% of those who download an app and opt in for push notifications keep the app on their phone for at least 30 days, compared with 29% who don’t opt in for such notifications.

Urban Airship analyzed more than 2,400 apps and 500 million push messages across the retail, media, gaming, entertainment, sports and gambling industries over six months for its report.

Looking specifically at retail apps, over those six months 46% of consumers who downloaded retail apps opted in for push notifications. Opt-in app users opened retail apps 12.54 times per month on average compared with 8.95 opens for those who opted not to receive push messages. At the end of six months, 21% of opt-in users still had the app on their mobile phones compared to 10% of opt-out users.

“Across the board, opt-in audiences open apps more frequently. Due to greater retention of opt-in users, the vast majority of an app’s total opens over time will be from users that receive push notifications,” Urban Airship says in its report. However, the notifications must add value to shoppers though coupons, sales notifications and other benefits the study says. “Beyond a subpar app, there’s probably no easier way to cause a mass exodus of users than by pushing self-serving, interruptive or annoying messages to the one device customers always have with them,” the study says. “If push messages aren’t relevant, many users find that it is easier to simply delete an app than to hunt for a preferences panel and toggle push notifications off.”